1. Technical Field of the Invention
The invention relates generally to communication systems; and, more particularly, it relates to receive processing (demodulation and decoding) of signals received within such communication systems.
2. Description of Related Art
Data communication systems have been under continual development for many years. In recent years, the development of piconet type communication systems has been under increasing development. A piconet may be viewed as a network that is established when two devices connect to support communication of data between themselves. Sometimes, piconets are referred to as PANs (Personal Area Networks). These piconets typically operate within a region having a radius of up to approximately 10 meters.
As is known, the Bluetooth® communication standard is the first such PAN communication standard that has been developed. In accordance with the Bluetooth® communication standard, the communication between the various devices in such a piconet is strictly performed using an M/S (Master/Slave) configuration. Each of the devices within such a Bluetooth® piconet is M/S capable. Typically one of the devices (sometimes referred to as piconet controller in this situation), or a first device within the Bluetooth® piconet, transmits a beacon signal (or an access invitation signal) while operating as the “master” device of the Bluetooth® piconet to the other “slave” devices of the Bluetooth® piconet. In other words, the “master” device of the Bluetooth® piconet polls the other “slave” devices to get them to respond.
However, other piconets may be implemented such that the devices do not operate according to such an M/S (Master/Slave) type relationship. In such instances, various piconet operable devices operate may be referred to as PNCs (piconet coordinators) and DEVs (user piconet devices that are not PNCs). The PNCs operate to coordinate the communication between themselves and the DEVs within the piconet. Sometimes, such a PNC may be implemented to operate as a master with respect to the 1 or more DEVs that operate as slaves, but this need not be the case in all instances—the strict M/S relationship is typically the case only in a Bluetooth® piconet.
In even some other instances, two or more piconets operate cooperatively such that at least two piconets operate such that they share at least one common device in a scatternet implementation. For example, in a scatternet, a single DEV may interact with two or more PNCs. This implementation will allow various devices within different piconets that are located relatively far from one another to communicate through the PNCs of the scatternet. However, within a scatternet implementation, a problem may arise such that each of the individual piconets must be able to operate in relative close proximity with other piconets without interfering with one another. This inherently requires a great deal of synchronization between the piconets, which may be very difficult to achieve in some instances. It is also noted that independently operating piconets, not implemented within a scatternet implementation, may also suffer from deleterious effects of interference with other piconets located within relative close proximity.
Some PAN communication standards and recommended practices have been developed (and some are still being developed) by the IEEE (Institute of Electrical & Electronics Engineers) 802.15 working group. These standards and recommended practices may generally be referred to as being provided under the umbrella of the IEEE 802.15 working group. Perhaps the most common standard is the IEEE 802.15.1 standard which adopts the core of Bluetooth® and which generally can support operational rates up to approximately 1 Mbps (Mega-bits per second).
The IEEE 802.15.2 recommended practice specification has been developed in an effort to support the co-existence of the IEEE 802.15.1 Bluetooth® core with virtually any other wireless communication system within the approximate 2.4 GHz (Giga-Hertz) frequency range. As some examples, the IEEE 802.11a and IEEE 802.11g WLAN (Wireless Local Area Network) standards both operate within the approximate 2.4 GHz frequency range. This IEEE 802.15.2 recommended practice specification has been developed to ensure that such a WLAN and a piconet may operate simultaneously within relatively close proximity of one another without significant interference with one another.
In addition, the IEEE 802.15.3 high data rate PAN standard has been developed in an effort to support operational rate up to approximately 55 Mbps. In this IEEE 802.15.3 standard, the PNCs and DEVs do not operate according to an M/S relationship as they do according to Bluetooth®. In contradistinction, a PNC operates generally as an AP (Access Point) and manages the various DEVs such that they are guaranteed to perform their respective communication according to their appropriate time slots thereby ensuring proper performance and operation within the piconet. An extension of the IEEE 802.15.3 high data rate PAN standard is the IEEE 802.15.3 WPAN (Wireless Personal Area Network) High Rate Alternative PHY Task Group 3a (TG3a). This is sometimes referred to the IEEE 802.15.3a extended high data rate PAN standard, and it can support operational rates up to 480 Mbps.
Yet another standard developed by the IEEE 802.15 working group is the IEEE 802.15.4 low data rate PAN standard that generally supports data rates within the range of approximately 10 kbps (kilo-bits per second) and 250 kbps.
There are several proposals currently being discussed for the IEEE 802.15.3 WPAN (Wireless Personal Area Network) High Rate Alternative PHY Task Group 3a (TG3a). Some of the ideas being discussed are based on a type of fast-frequency hopping sometimes referred to as time-frequency interleaving. These proposed solutions that employ time-frequency interleaving (that employ relatively fast-frequency hopping) are typically discussed as being implemented such that a single pulse is sent in each frequency band per frequency hop. The transmitted signal then hops between a fixed number (e.g., N) frequency bands in a periodic manner. In these proposed solutions, N is a typically a small integer (e.g. equal to or less than 7).
As briefly referred to above, as the proximity of piconets continue to grow ever closer, there is a problem that arises when the communication between the various piconets interfere with one another. For example, when communication between a user device and a piconet controller in one piconet is ongoing, and communication between another user device and its corresponding piconet controller in another piconet is also ongoing simultaneously, interference between the two paths of communication can cause degradation in the throughput of both of the communication paths. Moreover, even peer to peer communication between the two user devices in a first piconet and two other user devices in a second piconet may also generate the undesirable interference between the two piconets. This is particularly true in the wireless context.
Moreover, when adjacent piconets are transmitting using different hopping patterns, the signals can collide even once per period, resulting in a spreading gain of N. In most of these TG3a proposals, the time per hop is much greater than the inverse of the bandwidth of each frequency band, meaning that there is inevitably extra “dead time” that occurs between the various pulses of the communication within the piconet. One of the detrimental effects of such a proposal is that these proposed communication systems do not achieve the full available spreading gain. This directly results in suboptimal performance relative to what is possible using the available band spectrum of such communication systems.
There has been a great deal of development recently in seeking to enable the simultaneous operation of piconets within relatively close proximity with one another (without suffering significant deleterious effects such as degradation of performance, large numbers of collisions of transmitted symbols within the various piconets, and other such deleterious effects). Currently, there does not exist in the art a sufficient solution that may accommodate the undesirable effects of symbol collisions within such piconets in a satisfactory manner. While there have been some attempts to try to deal with minimizing these undesirable symbol collisions within such piconets, there does not yet exist a satisfactory manner in which symbol collisions (when they do in fact occur) may be dealt with while maintaining a very high level of performance for all of the devices within the piconet.
Clearly, there exists a great degree of room for improvement in the art of piconets to allow for the simultaneous operations of multiple piconets within relatively close proximity to one another without deleterious interference; this situation may generally be referred to as SOPs (Simultaneously Operating Piconets). If the advent of wireless communications (such as in the Bluetooth® space, the space addressed by IEEE 802.11 and IEEE 802.15 working groups and their corresponding standards and/or recommended practices, as well as other wireless communication spaces), is going to increase and become widely available, there exists a great need for such a solution to be presented to support and allow better and improved operation of SOPs.